There is a need to develop cell and molecular protection approaches for at-risk neurons in neurodegenerative diseases, and regenerative medicine offers designer cells to be used for factor-delivery in diseases like Parkinson's (PD) where we know that certain growth factors might, if delivered properly, have the ability to rescue a discrete population of nigrostriatal cells and hence slow or halt the progression of the disease. This proposal will use a novel cellular transplant approach to deliver glial cell line derived neurotrophic factor (GDNF) in comparable in vitro and in vivo bioassays of dopamine neuron degeneration. Three specific aims focus on which astrocytes, from different sources, can be used to deliver GDNF to at risk dopamine neurons in a culture model of PD as well as a well-accepted rodent model (6-hydroxydopamine, 6- OHDA lesions of the neostriatum) of the disease. Specific Aim 1 will establish the potential for autologous cellular repair by focusing on newly-generated "immature" astrocytes derived from the mouse brain (e.g. adult cerebral cortex and striatum), and bone marrow versus mouse embryonic stem cells. These candidate astrocyte populations will be transduced with an eGFP-GDNF lentiviral construct to determine which population(s) is most amenable to stable growth factor transduction and release of the growth factor, for subsequent testing in an in vivo lesion-protection model (Aim 3). Specific Aim 2 will look at adult human brain astrotypic and bone marrow-derived cells and their ability to be stably transduced with lenti-GDNF and release the growth factor as the mouse cells do in Aim 1. Specific Aim 3 will assay the potential protective actions of GDNF-releasing mouse and human cells in DA depleted mice. These studies will incorporate methods already developed and tested in our laboratories, including cell culture, electrophysiology, gene therapy, cell grafting, immunophenotyping, biochemical and behavioral testing at PD models and repair, with the goal of developing a new therapeutic protocol for at-risk neuron protection and rescue in human PD. The possibility of using autologous cells derived from brain or bone marrow offers a tremendous therapeutic advantage for exploiting stem/progenitor as well as differentiated cells to slow and even halt the course of devastating neurological disorders. It is hypothesized that astrotypic cells, derived either from brain or bone marrow, have the ability to be engineered to release therapeutic factors in PD.